The present invention relates to a yarn tensioning control and to a yarn stop motion, and more particularly to a combination of a ball tensioning control and an electronic stop motion.
Controlling the tension of yarn to obtain uniform tension of yarn feed in textile equipment and other equipment that manufactures or processes yarns and other types of strand material is an important aspect of obtaining quality in the material produced. Exceptionally proficient uniform yarn tensioning is obtained using a ball tension control of the type disclosed in the inventor's prior U.S. Pat. Nos. Re. 30,920, Re. 31,024 and Re. 31,041.
Preferably, such ball tension controls are mounted relatively close to the yarn supply, e.g. a bobbin or package, to minimize amplification of irregularity in tension caused by variations in friction during drawing of the yarn from the supply. Yarn breaks usually result from either a weakness at a point in the yarn being fed such that the tension applied by the ball tension control is greater than the strength of the yarn at the weak point or excessive resistance or friction as the yarn is withdrawn from the supply due to imperfections in the previous preparation of the supply, such as in winding of a package or bobbin preparatory to use in the equipment at which the yarn is supplied.
In addition to yarn tension controls, textile equipment and other types of strand processing equipment include stop motions that sense a break in the yarn or strand and signal a stoppage of the operation of the equipment until the break is repaired. The prior art is replete with various types of stop motions that operate mechanically, optically, electronically or otherwise, with electronic stop motions having an advantage of quick response. Stop motions are conventionally separate units from tension control units and located at a substantial spacing therefrom.
It has been discovered that when using ball tension controls most yarn breaks occur adjacent the supply and commonly immediately after the yarn passes the application or tension by the ball. This results in a time delay between the actual break and the sensing of the break by a stop motion located at a spacing from the ball tension control. Such time delay results in an increment of production by the equipment without uniform tension of the yarn feed, with resultant imperfection in the ultimate product.